import sys
read = sys.stdin.read
#readlines = sys.stdin.readlines
def main():
    x = int(input())
    if x >= 30:
        print('Yes')
    else:
        print('No')
if __name__ == '__main__':
    main() import sys sys read = sys.stdin.read read sys.stdin.read sys.stdin sys stdin read def main():
    x = int(input())
    if x >= 30:
        print('Yes')
    else:
        print('No') main x = int(input()) x int(input()) int input() input if x >= 30:
        print('Yes')
    else:
        print('No') x >= 30 x 30 print('Yes') print 'Yes' print('No') print 'No' if __name__ == '__main__':
    main() __name__ == '__main__' __name__ '__main__' main() main read = sys.stdin.read sys.stdin.read read def main():
    x = int(input())
    if x >= 30:
        print('Yes')
    else:
        print('No') def main():
    x = int(input())
    if x >= 30:
        print('Yes')
    else:
        print('No') main
import sys
read = sys.stdin.read
#readlines = sys.stdin.readlines
def main():
    x = int(input())
    if x >= 30:
        print('Yes')
    else:
        print('No')
if __name__ == '__main__':
    main()